Campers who travel with a vehicle to which a trailer is connected have increased, in accordance with demands of people who can afford a higher quality lifestyle.
While the trailer is connected to the vehicle using one pin, it is hard for a driver to keep a track of the trailer while driving. When the trailer is mounted in the vehicle, the trailer blocks a visual field of the rear view camera so that a rear side cannot be watched. Therefore, the rear view camera which is already mounted becomes useless, which does not help the driver drive the vehicle.
Recently, a backward movement assisting device for a vehicle which assists the driver to back the vehicle by detecting a folding degree of a joint between the vehicle and the trailer using an infrared sensor and then displaying the folding degree for the driver has been suggested.
However, in the case of the backward movement assisting device for a vehicle, an additional infrared sensor needs to be provided, which may increase cost.